The subject of the present invention is a wheel support for providing a rotatable connection between a wheel and suspension means of a vehicle with disk brakes, in particular a heavy vehicle the wheel flange of which has an outside diameter larger than the inside diameter of the brake disk used.
In these vehicles, a worn brake disk is generally replaced by dismantling the wheel-bearing unit.
However, the life of the bearings, which is generally longer than that of the brake disks, is guaranteed by producers only if the bearings are never dismantled after their initial assembly.
There is therefore a need to provide braking systems which enable the brake disk to be replaced without dismantling the bearing unit.
Solutions have been proposed to fulfil this need but, although they avoid dismantling the bearing, they have other disadvantages. For example, there are known disk brakes with braking bands which are divided into two parts connected to one another releasably to enable them to be replaced without the need to remove the bearing unit from the stub axle.
The main disadvantage of this solution is that it is difficult to ensure precise alignment between the two portions of the braking band, particularly in an axial direction, because of working tolerances both of the two parts of the braking band and of the connection between them.
As a result, the braking surfaces of the two assembled parts do not define a single braking surface and a stepped discontinuity is formed along the line of the joint between the two parts of the braking band. During braking, this step acts as a tool which removes friction material from the braking surfaces of the pads, causing rapid and uneven wear of the pads.
A further system of the prior art comprises a bearing, a brake disk, and a wheel hub, which are independent of one another and which can be connected by a set of screws, the screws being inserted in suitable holes provided in the wheel hub and in the bell of the brake disk and screwed into threaded holes in the outer ring of the bearing, clamping the bell of the brake disk between the wheel hub and the bearing, as can be seen in FIG. 2.
Although this solution does not require operation on the bearing during the replacement of the worn brake disk, it has the disadvantage of the presence of a fairly large bell which cannot be reused after the replacement of the disk.
Moreover, in this solution it is necessary to provide for two centring arrangements, that is, centring of the disk on the bearing and centring of the wheel hub on the disk bell, requiring at least four machining operations which are difficult and expensive to perform.
Furthermore, any use of axially slidable braking bands is rendered difficult and expensive by the large number of parts to be produced and assembled.
With regard to the structural behaviour of the systems of the prior art, they have highly stressed connection members such as the pins and the bolts which connect the two sectional portions of the brake disk, as well as the screws for connecting the wheel hub and the brake-disk bell to the bearing. In particular, during braking, the latter have to ensure that the joint they form can transmit the braking torque from the brake-disk bell to the wheel flange.